表面效应对锂离子电池正极材料LiMn_2O_4性能的影响  

Influence of surface effect to the performance of LiMn_2O_4 cathode material for lithium ion batteries

作　　者：胡国进[1,2] 欧阳楚英[2] 

机构地区：[1]江西教育学院,南昌330029 [2]江西师范大学物理系,南昌330022

出　　处：《物理学报》2010年第8期5863-5869,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10604023);江西省教育厅科研项目(批准号:JGG10398)资助的课题~~

摘　　要：应用基于自旋极化和广义梯度近似(generalized gradient approximation,GGA)的密度泛函理论计算,研究了锂离子电池正极材料LiMn2O4(001)表面原子和电子结构.发现表面和亚表面附近的原子在垂直于(001)面的方向上具有非常大的弛豫,这对LiMn2O4材料在锂离子电池中应用时发现的表面Mn的溶解现象有很大关联.由于表面效应,在LiMn2O4(001)表面只有三价Mn3+离子存在,而这些三价锰离子非常活跃,在该材料电极/电解液界面很容易发生歧化反应,从而加速了Mn的溶解.其他计算结果也和实验观察相符合.The surface geometrical and electronic structure of LiMn2O4（001） are investigated via a density functional approach within the spin-dependent generalized gradient approximation （GGA）. Large relaxations perpendicular to the （001） plane of surface and subsurface atoms are observed,which is partly responsible for the Mn dissolution problem of the material when used as cathode material for lithium ion batteries. Because of the surface effect,only Mn3 ＋ ions are observed at the LiMn2O4 （ 001 ） surfaces,which is very active for the disproportionation reaction occurs at the electrode /electrolyte interface. The calculated results are also in good agreements with experimental observations.

关 键 词：锂二次电池 表面弛豫 从头算 

分 类 号：TM912[电气工程—电力电子与电力传动]